There are more than 20,000 species of ants around the world and about 570 species in the United States. Of those, about 30 species are common household pests. When discussing ants, we will use three terms that reflect the size of the ants in a colony. If ants are “monomorphic”, it means all the workers are the same size. If they are “bimorphic”, they have two sizes in the colony. The larger ones are major workers and the smaller ones are minor workers. If they have three or more sizes of workers in the colony, they are considered “polymorphic”.
There are several things you can do to prevent ants from entering your home. The first step is exclusion. Go around the outside of your home and inspect it very carefully from an ant’s point of view. Ants can sense cool air and aromatic odors emanating from your home and will try to gain access. Check around the house at ground level and look for cracks in the foundation, voids around pipes, areas under stucco, peepholes in bricks and similar areas that ants can use to gain entrance. All these areas need to be sealed, caulked, screened or otherwise altered to prevent ants from using them to get into your home. Check around your windows and doors to make sure they close tightly. If the doors aren’t tight, you may have to install door sweeps on them. Check your bushes, shrubs and trees to make sure you don’t have any branches touching the roof. Don’t stack firewood, bricks or anything else next to your house or ants and other insects may find a good place to nest. If you have bushes or shrubs next to your house, periodically inspect them for aphids, scales and similar bugs as ants are attracted to the honeydew they produce. The ants will get on the plants and eventually find their way into your home. Don’t put flagstone or flat boards on the ground too close to your home or some species of ants will nest under them. On the other hand, mound-making ants will generally stay outside. They rarely leave their complicated and efficient homelike in the mound to enter homes. If you don’t want the ants making mounds in your yard, you can flood the nests with club soda or with white vinegar or food-grade DE. If you use the DE, mix 4 tablespoons per gallon of water. You can also use 1 gallon of orange juice diluted with 2 gallons of water and a dash of soap. If you prefer, you can also spread dry instant grits on the mound. The ants will eat it and not be able to digest it and die.
You can repel ants with a wide variety of products, including cinnamon, baking soda, Comet Cleanser, cedar oil, medicated baby powder, Tide, talcum powder, chalk, coffee grounds, borax, garlic, broken egg shells, bone meal, black or red pepper, peppermint, paprika, chili powder and mint leaves.
If you have ants going into your hummingbird feeder, you can put duct tape, sticky side out, on the wire holding the feeder, to deter them.
The best way to control them when they get in your home is with baits. Different species have different food preferences. Some species will take a wide variety of baits, while others are more fussy.
You can use a bait containing half baking soda and half powdered sugar and place it where you see foraging ants. You can also use instant grits, which they can’t digest or use 2 packets of Equal or NutraSweet, which contains aspartame, wherever you see the ants.
If the ants have a preferred food in your home, such as apple sauce, peanut butter, canned cat food, Karo Syrup, jelly or similar products, you can mix in small amounts of boric acid or borax or aspartame. Mix about 2% of any of these products in the food. Make sure you keep these baits away from children and pets. If the ants are dying near the baits, you are making it too strong and need to make a fresh batch with less boric acid or borax.
Here is a recipe for effective, homemade ant baits/traps that use borax. It attracts ants looking for either moisture or food. You will need: 3 c. water, 1 c. sugar, 1 tsp. borax or 2 tsp. food-grade DE or aspartame, 6 small screw-top jars with lids, such as jelly jars covered with masking tape, which will enable the ants to climb up the side. Mix the sugar, water and borax (or food-grade DE or aspartame) in a bowl. Loosely half-fill the jars with cotton balls or pieces of sponge or wadded paper towels. Pour up to ½ cup of the sugary mixture over the cotton balls, saturating them. Make several small holes in the lid. Screw the lids on the jars tightly.
If you smoke, always wear plastic gloves when making ant baits or they will sense the tobacco smoke on the baits and not go to it. Ants do not like cigarette or cigar smoke.
If you are finding ants in a classroom or office building and baits aren’t practical, then you can spray all of the foraging ants with Greenbug for Indoors, which is a cedar product and will kill the ants it hits and repel others. Here are a some of the ants most likely to be encountered in your home or yard.
There are three groups (Subfamilies) of ants that have pest (or guest) species. They are Myrmicinae,
Dolichodorinae and Formicinae.
Big-headed ants (Myrmicinae – Pheidole spp.)
Big-headed ants are bimorphic seed gatherers. The minor workers look like average ants. They gather the seeds and the major workers, with the enlarged heads, break them open. The major workers also defend the colony. These ants usually have small colonies of a couple of hundred individuals. Occasionally they will come in a house and make a nuisance of themselves by their presence. They won’t hurt anything. Niban Bait is effective in controlling them.
Acrobat ants (Myrmicinae – Crematogaster spp.)
Crematogaster are commonly called “acrobat ants”. This is a bit silly as they don’t do anything acrobatic except occasionally running around on four legs instead of all six. Acrobat ants are small, usually red and black, but there are all black species as well. The abdomen (last segment) appears flat on top when viewed from the side and is spade-shaped when viewed from above. There are two small spines on the thorax (segment between the head and abdomen). Acrobat ants are found over most of the United States. These ants are monomorphic.
Acrobats normally feed on the honeydew secretion of aphids and related insects that infest plants near your home. They may enter your home from the roof if there are any branches touching the house or from the ground. They will get between vigas and latillas in some homes and kick out a lot of loose sawdust. It looks like they are doing damage, but they aren’t. They are simply making a mess.
They will readily take sweet baits. You can make a bait with honey or Karo Syrup mixed with 2% boric acid or borax. Terro Ant Bait is also very good.
Little black ants (Myrmicinae – Monomorium minimum)
This species is commonly called “little black ants”, which is confusing as there are several species of little (small) black ants. Monomorium minimum are very small, shiny black ants that are monomorphic. These ants are found throughout the United States and southern Canada. Usually they nest outdoors where they can feed on the honeydew secretion of some insects, but occasionally they infest homes. In a home they will eat whatever is available, including bread, meats, sweets, fruits and vegetables. They will bite to protect themselves. They can be controlled using a bait made from two tablespoons each of peanut butter and jelly mixed with one tablespoon of boric acid or borax. Outside you can treat any nests with Greenbug for Outdoors, which is a cedar product.
Pharaoh ants (Myrmicinae – Monomorium pharaonis)
This species is commonly called “pharaoh ants”. They were first described in Egypt in 1758, hence their common name. They are very small, yellowish ants that are monomorphic. They got their name because they were originally discovered and described in Egypt in 1758. They are found in many areas of the United States. They will nest in any small, dark voids such as old boxes, empty bags, stacked newspapers,wall voids, under flooring, and/or especially near hot water pipes or heating
systems and even an unused salt shaker. Outdoors they will nest under objects on the ground, in potted plants, in stacked firewood or piles of bricks. They are primarily nocturnal and mainly come out to feed at night.
They have very large colonies, often exceeding a quarter of a million ants and a couple of hundred queens. They do not swarm to reproduce as most ants do, but using a system called “budding.” This is where reproductives just crawl off and mate nearby. Colonies of pharaoh ants usually contain many nests and it is essential to control all of them or you will never get rid of them. Never use synthetic pesticides in trying to control these ants as all you will do is cause them to split up and you will make the problem worse. Place baits such as half and half fruit juice and aspartame in soda straws. Cut the straws into one inch segments and put the segments where you have seen the pharaoh ants foraging. You can even tape them to the underside of tables. You can change the baits periodically by mixing peanut oil, sweet syrup, jelly or honey with 3% boric acid or food grade diatomaceous earth. Place the straw filled baits as close to the nests as possible. You can also put strained liver baby food, honey or peanut butter mixed with 2% boric acid or borax in small cups. Treat any cracks and crevices around the outside of the home with Greenbug for Outdoors.
Pharaoh ants are a major pest in hospitals where they have been associated with over 20 disease causing pathogenic organisms and they often enter isolation wards, operating rooms and patient rooms where they feed on blood and blood products and then contaminate sterile areas.
They are not native to the western U. S. and are brought in on commerce. They normally infest apartment complexes, hospitals and large commercial buildings in this area. They rarely infest homes, but it isn’t impossible.
Harvester ants (Myrmicinae – Pogonomyrmex spp.)
This group of ants are commonly called “Harvester ants”. They are comparatively large, 3/16” – 1/2” long, red to dark brown in color and they have a pair of spines on their thorax. They have a stinger and will use it if disturbed. Harvester ants are bimorphic. They make large mounds covered in gravel which retains heat and helps incubate the eggs in the nest below. These ants feed on seeds, which they gather and store for the winter. They spend almost all of their time gathering food for the winter. Occasionally they are distracted such as the colony of Texas harvester ants that live in my driveway. It is impossible for me to drive into my driveway without running over their mound. For some reason, only they know, they will not move off to the side. They spend a large part of the day rebuilding the mound that was damaged by my tire. I feel sorry for them because they don’t have time to forage for food and repair the damage, so I give them several handfuls of oatmeal and chicken feed every couple of days and an occasional apple muffin. The ants appear to like the offering as they gather it up quickly and take it to their storage area. While harvester ants are considered to be aggressive, in reality they are only very defensive.
During mating season, usually in late July or early August, swarmers from a harvester ant colony will fly high in the air. Most of the swarmers are males who would like to mate with the few accompanying females. Large swarms will occasionally fly over urban areas where they are not usually found and then land on the tall buildings in the area in order to rest. Occasionally they will come down chimneys or elevator shafts, much to the consternation of the inhabitants of the building. The good news is that the swarming harvester ants are not able to sting. The bad news is that there are a lot of them and they tend to congregate in large numbers and will be a nuisance. The best product to use to control harvester ants is Niban Bait, a commercial grain-like bait that is made from boric acid.
Imported fire ants (Myrmicinae – Solenopsis invicta)
The imported fire ants can be very dangerous. They are polymorphic and reddish-brown to black in color. They have severe stings that can cause blisters and allergic responses to the venom as well as anaphylactic shock. Over 30,000 people a year in this country seek medical attention from the sting of these ants.
Fire ants have successfully invaded many southern states. They have been found in Florida, Georgia, South Carolina, North Carolina, Tennessee, Alabama, Arizona, New Mexico, Mississippi, California, Louisiana, Arkansas, Texas and Oklahoma. Their mounds can be 2 feet in diameter and a foot and a half high. A single colony can contain close to a quarter million ants.
Fire ants will eat both plant and animal products including rodents and some reptiles. They will feed on a wide variety of plants, including strawberries, potatoes and corn. Queens in the colony will need proteins, so when you mix baits for these ants you have to make sure they are protein-based. These ants are attracted to magnetic fields and will get in transformers, air conditioners and other electrical equipment. One good thing about fire ants is that they like to feed on ticks. If you have fire ants in your yard, you won’t have ticks. They will also feed on fleas, cockroaches and several species of flies.
When you control these ants, make sure you dust any electrical equipment outside with food-grade diatomaceous earth, Comet cleaner or talcum powder. This will keep the ants out of these area. For a bait, you can mix boric acid or aspartame with sugar, jelly, honey or pet food. You can flood their nests with one gallon of orange juice mixed with two gallons of water and a cup of dish soap. You can also pour a couple of 2-litre bottles of Coca Cola down the mounds.
Thief ants (Myrmicinae – Solenopsis molesta)
Thief ants are very small ants that are related to fire ants, but resemble pharaoh ants. They are less than 1/16th of an inch long. The best way to tell them from pharaoh ants is to examine the antennae with a magnifying glass. The club on the end of the antennae has two segments in thief ants and three segments in pharaoh ants. Thief ants get their name from their habit of entering the colonies of other ant species and stealing their food.
These ants are found throughout the United States but are more common in the east and south. Outside they nest under debris on the ground, or under rocks, boards or logs. In a home, they will nest in wall voids and behind baseboards.
Baits do not work well for these ants as they don’t bring enough back to the colony for it to work. If you can find out where they are nesting, you can put some food-grade diatomaceous earth in the void. Cinnamon will repel them from areas you don’t want them. You can also spray the ants with Greenbug for Indoors and use Greenbug for Outdoors in all the cracks and crevices around the outside of your home.
Pavement ants (Myrmicinae –Tetramorium caespitum)
Pavement ants are small, monomorphic, brown to black ants covered in small stiff hairs. The head and thorax are covered with small grooves that are easy to see. There are two small spines on the thorax. These ants frequently nest under concrete slabs as their name implies. They will also nest under the slab in homes and then enter the home through the expansion joints or where plumbing penetrates the slab. Once inside, they will nest inside of walls or other voids, often close to a heating source for the warmth.
They originated in Europe and are now found throughout much of the U. S., and are major pests in the northeast and midwest. They are also common in areas of California and New Mexico. They can sting and bite if disturbed. Pavement ants feed on the honeydew secretion of aphids and other insects as well as on seeds. They have very large colonies. Pavement ants readily take baits. Mix two tablespoons of peanut butter and jelly or honey with a tablespoon of boric acid or borax. If you can find their nest, you can dust it with food-grade diatomaceous earth or spray it with a cedar product such as Greenbug for Outdoors.
Argentine ants (Dolichoderinae – Linepithema humile)
Argentine ants are small, monomorphic and brown in color. They are one of the most successful ants species on the planet. They have huge colonies and when they move into an urban area, they displace any native ant species. Unlike other ants who fight when they encounter other colonies of their same species, Argentine ants will merge and form super-colonies, and in some cases, mega-colonies. There is one mega-colony of Argentine ants in Europe that extends over 3,700 miles and encompasses parts of Spain, Portugal, France and Italy. This mega-colony is estimated to contain hundreds of billions of ants. Argentine ants came to the United States in 1891, landing in New Orleans. Since then they have spread to several other states. They were first found in California in 1905 near Ontario. Three years later they were found in Alameda, East Oakland, San Francisco, San Jose, Los Angeles, Azusa and Upland. The Argentine ant is now found in almost all urban areas of California where it is a major household pest. Besides California and Louisiana, there are records of these ants in Utah, New Mexico, South Dakota, Arkansas, Illinois, Florida, Alabama and Hawaii.
Outdoors I recommend using a very good cedar product called Greenbug for Outdoors. Cedar will repel most ants including Argentine ants. Spray this around your foundation every couple of days for awhile. After a couple of weeks, spray it once a week. Soon you can do it every two or three weeks. It doesn’t have the residual power of a pesticide, but it isn’t dangerous either. You can also use aromatic cedar mulch which will control them for several months. Also; Remove all mulch (other than aromatic cedar mulch) from around the foundation of the building. Seal all cracks and crevices. Do not let any branches touch the building. If you find the nests outdoors, flood them with orange juice in soapy water
Argentine ant workers have a sweet tooth, so indoors you can use sweet baits. Mix honey or light Karo Syrup with aspartame or 2% boric acid or borax. However, queens also have high protein requirements so you may want to make some peanut butter or fish meal baits with 2% boric acid or borax. Keep all of these baits away from children and pets.
Populations indoors are usually smaller and less active. Find the most active areas and sprinkle the areas with baking soda, Comet, Tide laundry soap, talcum powder or food grade diatomaceous earth. You should also place any of these materials in any cracks and crevices, wall voids and electrical outlets. If you see trails of ants, you can spray them with bleach or vinegar. Never spray pesticides on the ants as all you will do is kill a few and the rest will go to other areas of the house. Cedar oil repels them and the best commercial product is Greenbug for Outdoors.
Pyramid ants (Dolichoderinae – Dorymyrmex spp.)
Pyramid ants are reddish-brown or black and are monomorphic. They have a distinct pyramid-shaped projection on the back of their thorax, hence their name. These small ants rarely come into homes. They usually make many small mound around the yard and in cracks in sidewalks and on patios. They are found in most of the southern states and in California.
They will readily take a sweet bait such as jelly or honey mixed with aspartame if they do come indoors. Terro bait is a good commercial bait. Outside pour a cup of baking soda on the mounds, wait about a half an hour and pour a cup of vinegar on the mounds. You can also pour a 2-litre bottle of Coca Cola or Club Soda down the mound. Push a stick into the mound entrance and move it around to make the hole larger before pouring the Coca Cola or Club Soda in.
Odorous house ants (Dolichoderinae – Tapinoma sessile)
Odorous house ants are small dark reddish-brown to black ants and are monomorphic. They will follow each other in single file when entering a building. Outside they nest under objects such as rocks, boards, or any kind of debris. When they come in the home, they can nest in wall voids. If the house has a crawl space, they will nest in that area and come into the house to forage for food and water. Odorous house ants have multiple queens in a colony and hence, have large colonies.
These ants are found in all of the continental United States and adjoining parts of Canada and Mexico. They are probably the most common ant found in homes, except in areas where Argentine ants live.
They do not bite or sting. The body of the odorous house ant is relatively soft and can be easily crushed. When this occurs, a very unpleasant “coconut” odor is apparently released. I can say that in over 40 years I have never sniffed an ant so can’t vouch for the smell. An average Odorous House Ant colony will have 10,000 to 40,000 members and several queens. Mating and swarming takes place in the nest and new colonies are formed by budding.
A good bait for controlling these ants indoors is two tablespoons each of peanut butter and jelly mixed with a tablespoon of boric acid or borax. A good commercial bait is Terro Ant Bait which is made from boric acid. Treat areas where they are entering your home with Greenbug for Outdoors, which is a cedar product.
Ghost ants (Dolichoderinae – Tapinoma melanocephalum)
Ghost ants are very small, have a black head and thorax and whitish abdomen and legs. They are monomorphic. They are common in Florida and Hawaii and are also found west to Texas. It is not known where they originated from, but they were described from Indonesia and have been found in many parts of the world, including Africa, Australia, New Zealand, Japan, and much of Polynesia
These ants are highly adaptable and can nest outside or in your home. They may have several sub-colonies in one structure They will nest in walls, behind cabinets, behind baseboards and in potted plants. They are very fond of greenhouses. Indoors they prefer sweet foods such as syrups, sugar and cakes. Outside they will feed on dead insects and the honeydew secretion of aphids.
Ghost ants do not swarm. They reproduce by budding as does the pharaoh ants. Budding occurs when one or more reproductive females leave a colony with several workers and find a new location to establish a home. A good bait is two tablespoons each of peanut butter and jelly or honey mixed with one teaspoon of boric acid or borax. You can put the layer of food grade diatomaceous earth on the soil of any potted plants. When you water it will mix in with the soil and remain effective.
White-footed ants (Dolichoderinae – Technomyrmex difficilis)
White-footed ants are small, black ants with white tarsi (end of legs). They are monomorphic. These ants are one of the hardest species to control. There are several reasons for this, but the primary reason is their reproductive habits seem to be designed to confuse people. Winged female white-footed ants only live a little over a year after starting a colony. When she passes on she is replaced by a wingless female who mates with a wingless male and who is capable of multiple matings. These wingless reproductive white-footed ants can comprise up to half the colony. In other words, they can reproduce faster than almost any other species of ants as they have so many queens laying eggs almost constantly. Because of their multiple queens constantly reproducing, come colonies can contain up to 3 million individual ants and half of these can be reproductives. The good news is that they don’t bite, sting or cause any damage. They are simply a nuisance by their numbers.
These ants are embedded in central Florida and have also been found in South Carolina, Louisiana, California in this country and in Montreal, Quebec, Canada.
White-footed ants feed on the nectar of some plants and the honeydew secretion of aphids and similar insects. They will actually protect these insects from their natural predators. Outdoors white-footed ants can be found under the bark of trees or even in the old galleries of termites in wooden structures. They can also live in compost piles, leaf litter, under rocks and in outdoor furniture. They can move into homes and nest in attics, under roof shingles, in walls, and similar areas. One colony can have several branches or “satellite” colonies in or around a single home.
Yellow ants (Formicinae – Acanthomyops spp.)
Yellow ants are medium size ants and are yellow in color. They are monomorphic. These ants are found throughout the Midwest and New England and more commonly in the southern states including Texas and New Mexico. They feed on the honeydew secretion of aphids and similar insects. They will nest under debris on the ground around a house and in foundation walls but rarely forage in a home. Treating the areas near the foundation with Greenbug for Outdoors will help control them If they come in the house, use a sweet bait mixed with aspartame to control them.
Carpenter ants (Formicinae – Camponotus spp.)
Carpenter ants are large, polymorphic and are black, reddish-brown, red and black or light brown in color, depending on the species. The thorax is evenly convex when viewed from the side. That differs them from field ants who are also large but have an indented thorax. Field ants are rarely household pests.
Carpenter ants are found throughout the United States. There are a number known species. Five species that are common include Camponotus pennsylvanicus, Camponotus modoc, Camponotus herculeanus, Camponotus laevigatus and Camponotus vicinus.
Most species are active in the late afternoons and at night. They will nest under the slabs of homes and enter through expansion joints or around plumbing. They are also found in crawl spaces under homes that have them. They will be most common in areas where there is nearby moisture. If there is damp wood available, they will make galleries to make their nests. The galleries will follow the grain of the wood. If left alone, they can hollow out and destroy structural wood. They don’t eat the wood, they just carve out areas and create wood segments (frass). If they are in the house, they will forage for any foods available, including pet foods, candies, syrups, sugar and other sweet products. They will also feed on any fruits they encounter and will root through the garbage looking for grease, fat or meat scraps. You can use a bait made from two tablespoons of honey or jelly mixed with a teaspoon of boric acid and place it where the ants are foraging (keep out of the reach of children and pets). You can also put out open packets of Equal (aspartame), which they will take.
To prevent carpenter ants from entering your home, you should remove or repair all damaged wood that has a moisture problem. Make sure your gutters are clean so water doesn’t back up and damage the siding or the roof and that no branches are touching the house. Store all firewood off the ground and away from the house. Remove all dead stumps and logs. I also recommend dusting your crawl space, if you have one, with food-grade diatomaceous earth. This can be done with a power duster.
If you find a nest you can spray it with a good natural pesticide, not a synthetic one that will do more harm than good.
Crazy ants (Formicinae – Paratrechina longicornis)
Crazy ants are black or brown, appear thin and have very long legs. They run around erratically, giving them the name. They are monomorphic. These ants are found along the coasts of California and southern Oregon in the west. They originally came from India. They live in a variety of habitats, including areas that are very dry to areas that are wet. They will nest under wood, in tree cavities, in or under any debris left on the ground for a long time and even in potted plants. They reproduce by budding rather than by swarming.
They feed on a variety of foods, including sweets and even other insects. They particularly like house flies when they can catch them. They will also feed on the honeydew secretion from aphids and scales.
Baits should consist of sweets or proteins mixed with about 5% boric acid. They love garbage, so make sure garbage storage areas are as clean as possible. It will help to put food grade diatomaceous earth around the house under any bushes or shrubs. If you can find the nest, spray it with a good natural pesticide such as Greenbug for Outdoors.